A control system for a projectile often requires a measurement of the projectile velocity, in order to improve the projectile navigation and accuracy. The need for the projectile velocity has become increasingly important due to the desire for accuracy, particularly at longer ranges. Conventional solutions to the measurement of the projectile velocity propose using GPS signals to obtain the projectile velocity and position measurements, as well as using Doppler measurements.
Projectile flight velocity estimates are conventionally used for navigation or fuzing purposes. These estimates are typically processed from accelerometer measurements, which could lead to measurement bias errors in the velocity estimates.
Although the conventional solutions have proven to be satisfactory, they are faced with certain limitations. As an example, GPS measurements cannot be used for all applications since some projectiles might not be readily equipped with GPS. More specifically, using GPS measurements for a projectile might be unacceptable for at least the following two reasons: First, if the projectile is not already equipped with GPS capability, fitting an entirely new, typically complicated GPS system, into the existing design might be problematic. Second, it might be desirable to maintain the projectile guidance capability in the absence of GPS measurements.
As another example, Doppler radar measurements might be limited to certain types of projectiles. More specifically, using a Doppler radar might in certain circumstances be unsatisfactory, particularly if the projectile is not equipped with a radar seeker, or if the projectile does not have sufficient capability or physical space to enable the addition of a new radar seeker. In addition, it might be desirable to maintain a passive, non-RF (non-radio frequency) emitting design.
What is therefore needed is an onboard sensor suite that is capable of determining the munition muzzle velocity without modification to the gun system, and that is further capable of accurately determining the in-flight munition velocity independently of GPS measurements. The need for such an onboard sensor suite has heretofore remained unsatisfied.